Relay contact



Mardi i2, 1940.

A. H. LAMB RELAY conn'r Filed n. 1v, 193s Patented Mar. 12, 1940 UNITED STATES PATENT OFFICE RELAY CONTACT Application December 17, 1936, Serial No. 116,407

11 Claims.

This invention relates to relay contacts and more particularly to contacts for use in low power or sensitive relays of the instrument type.

A relay of the instrument type in which two 5 flexible contact blades engage simultaneously with two permanent magnet contacts is shown in Fig. l of my prior Patent No. 2,039,230, granted April 28, 1936. The normal commercial variationsin the thickness and strength of the thin l0 flexible blade material resulted in variations in operating characteristics, due to the minute forces established by a sensitive instrument type relay for eiecting contact engagements, that necessitated a careful adjustment of the parts to 1l obtain a reliable closure of both contacts.

An object of this invention is to provide instrument relay contacts of double type in which the contact blade is iirmly engaged with a pair of xed contacts when actuated by a moving system of high sensitivity. An object is to provide relay contacts which include a rider of magnetic material on a contact arm, and a pair of magnet contacts positioned to be bridged by the magnetic rider. An object is to provide relay contacts in'- cludlng a pair of relatively stationary contacts comprising the opposite poles of a magnetic circuit, and a contact arm carrying a rider of magnetic material which is ilrmly engaged with both of the poles or contacts when the contact arm ,o is moved into proximity to the contacts. More particularly, an object is to provide relay contacts of the type stated in which the magnetized contacts and magnetic rider are shaped to permit a rolling ilt or self-adjustment of the magnetic u rider upon the magnetized contacts.

A further object is to provide a relay contact system which affords a good contact engagement in spite of arcing at the contacts; the system including a contact arm and two contacts that are spaced apart for sequential engagement by the contact arm, whereby/ the pitting is restricted to one contact and the other contact is protected from destruction by the arcing.

These and other objects and advantages of the 5 invention will be apparent from the following specification when taken with the accompanying drawing in which:

Fig. 1 is a front view of a relay having contacts embodying the invention;

Fig. 2 is a fragmentary vertical sectional view showing, in side elevation, the magnetic contact system and the contact-separating mechanism;

Fig. 3 is a schematic diagram of one type of relay circuit in which the novel contacts may be u incorporated;

(Cl. 20G-56) Figs. 4 and 5 are schematic diagrams illustrating other relay circuit connections; and 1 Fig. 6 is a fragmentary sectional view of a contact system that is adapted for use in a highly inductive controlled circuit.

The contacts contemplated by this invention may be' used with various types of relays and, for purposes of illustration, the invention is shown as applied to a relay of the general type disclosed in my prior Patent No. 2,014,388, granted September 17, 1935. In the drawing, the reference numeral I identifies the insulating base of an instrument type relay comprising the permanent magnet 2 having poles 2, 2 between which the moving system, i. e. coil 3 and pointer 4, are pivotally mounted. The pointer 4 moves over a graduated scale 5 on a scale plate 6, and carries a contact or rider 'l of magnetic material. The pointer or contact is a somewhat flexible strip of sheet metal and the cylindrical contact 1 is secured upon the squared end of the pointer 4, for example by swaging. A pair of small permanent magnets 8, 9 are supported from the base I, by an arm III, with their rounded ends positioned to be bridged across by the rider 1 in one position of the pointer 4. Bushings II insulate the magnet contacts from the arm I0, which may be of iron, and terminal lugs I2 are secured to the contacts by the nuts I3 which secure the contacts to the arm.

The illustrated relay includes a stop I4 on a spring ar-m I5 for arresting the maximum swing of the pointer 4, and pusher means for separating the contact 1 fromthe magnet contacts 8, 9. The illustrated pusher mechanism is described in my prior Patent No. 2,014,388 and the exact construction of this mechanism forms no part of the present invention. The pin I6 on the pusher arm I1 may be moved in a counter-clockwise direction, Fig. 1, to force the contact arm 4 away from the magnet contacts 8, 9, either by the manually operable knob I8 'or the mechanically operated arm I9. Reference is made to the prior patent for a detailed description of this mechanism. a

The magnet contacts 8, 9 are parallel to each other and arranged approximately symmetrically with respect to the plane of movement of the axis of the magnetic rider l on the pointer 4, see Fig. 2. The polarity of the contacts is reversed, as indicated by the notations N and S, and the magnets therefore form a single magnetic circuit that includes, at their inner ends, a part of the arm I0 when the latter is iron or magnetic ma terial. The gap between the outer rounded ends a ,rider 1 into firm engagement with one of the magnetic contacts and, substantially instantaneously, the increasing magnetic ilux due to the decreased length or the air gap in the magnetic circuit, rolls the rider 1 upon the contact which it first engages into an equally firm engagement with the second contact. It is possible, of course, that the rider 1 will approach the magnet contacts 8, 8 in such manner that it engages both contacts simultaneously, but it is more probable that slight variations from exact symmetry of the path of rider 1 in the magnetic field will cause rider 1 to strike one contact just prior to its engagement with the second contact. The pointer 4 is of small cross-section and ilexes readily to permit the slight rolling movement of the rider 1 on one Contact.

'I'he simplest form of relay circuit in which the contacts may be used is shown in Fig. 4. A source of current 28 and a load or alarm device 2I are serially connected between the contacts 8, 9 and the controlled circuit is completed when the magnetic contact 1 is bridged across the magnet contacts. This circuit is particularly advantageous when it is inconvenient or undesirable to connect a contact-carrying spring to the pointer 4.

As shown in Fig. 4, one side of the current source 28 may be connected to the pointer 4 by a ilexible lead or spring 22, while the other terminal of the current source is connected through load or alarm devices 23, 24 to the respective contacts 8, 9. Alternatively, the current source may be connected between contacts 8, `9 through the device 23, and the load device 24 may be connected between the current source 28 and pointer 4 by a flexible lead or spring 22.

The contacts 8, 9 are separated by load devices in the Figs. 4 and 5 circuits, but they may be connected in parallel, as shown in- Fig. 6. The magnet contact 9 in this form of the invention is somewhat shorter than the magnet contact 8, and their contact surfaces are displaced, along the path of the contact 1, by a small distance a, whereby contact 1 engages magnet 8 before magnet 9', and is separated from magnet 9' just prior to its separation from magnet 8. This arrangement is particularly advantageous for heavy duty or where the controlled circuit is highly inductive. This condition is discussed in Patent No. 2,014,388 and, as there described, a separate switch was provided to relieve the magnetic contacts of the duty of opening an inductor circuit. According to this invention, the auxiliary switch is eliminated, since ail arcing takes place between contacts 1 and 8, and the contact 8 and co-operating section of contact 'l may be severely oxidized or pitted without aiecting the good contact engagement obtained between the contact 9 and the l.cooperating section of the contact 1. The sequential contact engagements and contact separations may also be obtained with magnet, contacts 8, 8 of equal length by offsetting the plane of symmetry of contacts 8, 9 from the plane of movement of the axis of the contact 1.

It will be apparent that the invention is not limited to the particular embodiments herein illustrated and described. A single miniature horseshoe magnet could be substituted. for ex` ample, in the Fig. 6 form oi.' the invention. Furthermore, plane or combinations of plane and rounded contact surfaces could be used in place or the illustrated rounded surfaces to obtain the automatic rocking and sliding adjustment of the magnetic material contact on the permanent magnet contacts. It is therefore to be understood that many variations in the form, shape and relative location of the parts fall within the scope o! my invention as set forth in the following claims.

I claim:

l. A contact system for a sensitive relay device of the instrument type comprising a movable member, a contact of magnetic material lcarried by said movable member, and a pair of contact members positioned at opposite sides oi.' the path of movement of said. member to be bridged by said contact, said contact members being magnets having poles of opposite polarity for engagement by said contact.

2. An instrument type contact system com-A prising a movable member, a contact of magnetic material on said member, a pair of magnets forming contact members at opposite sides of the path of movement of said member to be bridged by said contact in one position of said movable member, and means supporting said magnet Contact members and insulating the same from each other.

3. An instrument type contact system comprising a movable member, a contact of magnetic material on said member, a pair of magnets forming contact members at opposite sides of the path of movement of .said member to be bridged by said contact in one position of said movable member, said contact and said contact members having rounded contact surfaces, and means supporting said magnet contact members and insulating the same from each other.

4. An instrument type contact lsystem eomprising a movable member, a contact of magnetic material on said member, a pair of magnets forming contact members to be bridged by said contact in one position of said movable member, and supporting means insulating said contact members from each other, said contact members having poles of opposite polarity positioned approximately symmetrically with respect 0 Ehe path of movement of said magnetic con- 5. An instrument type contact system comprising a movable member, a cylindrical contact of magnetic material carried by said member, and a pair of magnet contact members positioned on opposite sides of and substantially symmetrically with respect to the path of movement of the axis of said cylindrical contact, said pair of contact members having poles of opposite polarity to which said magnetic material is attracted when moved into proximity to said contact members by said movable members.

6. A contact system as claimed in claim 5, wherein said movable member is flexible under the force with which said contact is attracted by said magnet contact members.

7. An instrument vtype contact system coml successive engagement by said magnetic material contact upon movement of the same into bridging position and i'or successive separation therefrom in reverse order upon movement of the magnetic material contact out of bridging position, whereby arcing takes place at only one of said pair of contacts when they are connected in parallel.

8. A contact system as claimed in claim '7,

wherein said magnetic means comprises a pair of permanent magnets.

9. A contact system as claimed in claim 7, wherein said magnetic means comprises a pair 0i' permanent magnets at opposite sides of the path of movement of said magnetic material contact.

10. A contact system as claimed in claim 7, wherein said magnetic means comprises a, pair of permanent magnets symmetrically arranged with respect to the path of movement of' said magnetic material contact, and said positioning means locates the contact surface of one-magnet in advance of the contact surface of the other magnet.

1l. An instrument type contact system comprising a flexible movable member, a contact of magnetic ,material secured thereto, and means forming a magnetic circuit having spaced poles constituting contact surfaces to be bridged across by said magnetic material contact in one position of said movable member, said poles being at opposite sides of the path of movement of said magnetic material contact and longitudinally vdisplacedy along that path.

ANTHONY H. LAMB. 

